1. Field
The present disclosure relates generally to inspecting objects and, in particular, to performing nondestructive inspection of objects using ultrasound inspection. Still more particularly, the present disclosure relates to a method and apparatus for inspecting composite objects with limited access using ultrasound inspection.
2. Background
In manufacturing aircraft, vehicles, and other structures, inspection of parts used to form these structures is often performed to determine whether the parts will have desired parameters for a desired performance of the part. Additionally, the structures and parts are inspected as part of normal maintenance when the aircraft, vehicles, and other structures are in use.
Nondestructive testing is commonly performed on these parts. Nondestructive testing is used to evaluate the properties of a part without altering the ability to use the part in service.
Ultrasound testing is a type of nondestructive testing. Ultrasound testing is often used to perform inspections on aircraft parts that include or are comprised of composite materials. Ultrasound testing involves transmitting sound waves through a test object, such as an aircraft part or structure.
Ultrasound testing is commonly performed using a transducer. The transducer is configured to send sound waves into a test object and detect a response to the sound waves. The response to these sound waves is analyzed to determine whether inconsistencies are present in the test object.
The transducer is typically coupled to a surface of the test object. This coupling involves physical contact between the transducer and the test object. In most cases, a coupling medium is also employed. For example, water, oil, a water-based gel, or some other liquid may be used. A semi-solid material like rubber can also be used as a coupling medium. This coupling medium is often used to reduce the acoustic impedance between the transducer and the test object.
In some cases, coupling the transducer to the surface of the test object may be more difficult to perform than desired. These test objects may have various shapes and configurations. These shapes and configurations may make inspection more difficult. For example, curved shapes, corners, fittings, or other non-planar structures may be more difficult to inspect than desired.
Further, some locations within an aircraft may be more difficult to inspect than desired. For example, enclosed spaces within the aircraft are particularly difficult to inspect because other structures may obscure the path of the ultrasound inspection system. These obscured locations may have mechanical and/or electrical structures obscuring the path of the inspection system to the surface of the object under test.
Additionally, some enclosed spaces within an aircraft may limit the type of inspection that may be used to inspect the structures within the enclosed spaces. For example, an enclosed space may be smaller than the transducer array for the ultrasound inspection system.
One example of an enclosed space may be a cavity in a structure such as a fuel tank. Access to the cavity may be through an opening that may not allow access by currently used ultrasound inspection systems.
Moreover, some currently used inspection systems for small spaces are not as accurate as desired. For example, the design of currently used ultrasound inspection systems may not be able to inspect as much of the structure within the space as desired by the operator. For example, when inspecting fuel tanks, wing boxes, electrical boxes, ventilation systems, or other structures, some currently used inspection systems may not be capable of inspecting as much of these structures as desired.
Further, when a selected structure to be inspected in an aircraft is obstructed by other structures, disassembly of one or more of the structures blocking the selected structure may be needed to perform inspection of the selected structure. During routine maintenance, disassembly of a structure may take more time or manpower than desired. As a result, disassembly of the structure to inspect all surfaces of the structure may be more expensive than desired.
For example, when ultrasound testing is used to inspect the internal surfaces of a wing of an aircraft, the wing may need to be disassembled. This disassembly of the wing may put the aircraft out of service for longer than desired.
As a result, these surfaces may not be inspected as often as desired. In some cases, disassembly of some or all of the wing may be infeasible. Thus, inspections require using other techniques other than ultrasound inspection systems. These systems may be more expensive or may not provide a desired level of inspection.
Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.